This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Superlattices are ordered arrangements of multiple distinct materials in which new or improved mechanical or electrical properties are achieved through controlled variation in the composition, scale, or superstructure (e.g. periodicity). These structures may be employed in a wide range of technologies including lasers, light emitting diodes (LEDs), photodetectors, fuel cells, and thermoelectric devices. Typically, the variation in composition of these materials is in only one dimension and the scale of composition variations is on the order of nanometers.
Conventionally, the majority of layered superlattice structures have been fabricated using techniques requiring gas-phase reagents, and often in high temperature, low pressure (high vacuum) environments (e.g., chemical or physical vapor deposition). These vapor-based methods have significant drawbacks including: cost and energy intensity, requirement of specially-designed substrates and expensive precursors of limited chemistries, difficulty or inability to deviate from planar processing, and limited chemical compositions.
Other solution-based techniques such as spin-coating or chemical bath deposition often sacrifice precision of thickness of the deposited layers. Further, bonding between successive layers is typically non-covalent in solution-based depositions, meaning that interfaces between materials may be very poor conductors of electricity.
A need exists for improved technology, including a method of fabrication of superlattices and aperiodic layered structures using solution deposition.